Social media are not the only source of good training data, have you seen how many security cameras are in London, for example? To be training data it also has

Social media are not the only source of good training data, have you seen how many security cameras are in London, for example? To be training data it also has to be labelled - security camera footage alone is not a good source of training data, unless it can be correlated e.g. with swipes of an ID card through a door or something, to provide the label.